Unmanned underwater vehicles (UUVs) and other structures or containers are used to house and deliver electronics, sensors, cameras and other equipment in a marine environment. Often, these structures are expendable, i.e., they are designed to be used once or continuously over a finite period of time without expectation that they will be retrieved. For example, a housing that contains acoustic sensors and communications equipment for monitoring an area of the ocean for a specific period of time can be dropped in the ocean and left on the sea floor to collect data during that time and communicate it to the surface. At the end of the period for which monitoring is desired, i.e., at the end of its mission, the housing with its enclosed equipment must be either retrieved from the surface, which may be impractical or expensive, or left behind to degrade in the natural environment over a period of time. However, there is currently no known way to design and produce these structures so that their rate of degradation can be controlled.
Furthermore, these vehicles and structures are typically special-purpose devices, rather than mass produced, and may therefore benefit from the efficient fabrication afforded by the 3-D printing processes known in the art. Currently, modified polylactic acid (PLA), (poly)hydroxybutyrate (PHB), or polyhydroxyalkanoate (PHA) materials are typically used as biodegradable 3-D printing materials. While these materials are biodegradable in a marine environment, the rate of degradation of a structure printed from these materials cannot be selected or control. There is an unmet need to produce marine biodegradable 3-D printable structures for which the rate of degradation of each structure can be selected for a particular mission.